Universidade Federal de São Carlos, Departamento de Botânica. Rodovia Washington Luis, km 235. Caixa Postal 676, CEP 13565-905, São Carlos, S.P., Brazil.
Environ Sci Process Impacts. 2014 May;16(5):1029-34. doi: 10.1039/c3em00550j.
Cadmium (Cd) is an important industrial and toxic metal. Its fate and toxicity in the environment may be mediated by association with dissolved organic materials excreted by phytoplankton. The aim of the present study was to investigate the trophodynamics and toxicity of Cd complexed with Cylindrospermopsis raciborskii exudates in a plankton food chain. The microbial loop involves heterotrophic bacteria as the primary consumer, which is supplemented with a Cd-exudate complex. The secondary consumer (protozoan Paramecium caudatum) was fed on the bacteria, and the tertiary consumer (copepod Mesocyclops longisetus) on the protozoa. The Cd complexing properties of the exudate were determined before the experiments, to ensure that all Cd was furnished to the organisms as the organic complex alone. The results showed that free Cd2+ ions caused the highest observed toxicity to bacteria, while Cd complexed to the cyanobacterial exudate was less toxic, but could be bioavailable and transferred through the food web. This study is a contribution to aquatic ecosystem management and to current knowledge of Cd dynamics, bioavailability and interaction with aquatic planktonic organisms.
镉（Cd）是一种重要的工业重金属和有毒金属。它在环境中的命运和毒性可能与其与浮游植物排泄的溶解有机物质的结合有关。本研究的目的是研究与 Cylindrospermopsis raciborskii 分泌物结合的 Cd 在浮游生物食物链中的营养动态和毒性。微生物环涉及异养细菌作为初级消费者，补充 Cd 分泌物复合物。次生消费者（原生动物 Paramecium caudatum）以细菌为食，三次消费者（桡足类 Mesocyclops longisetus）以原生动物为食。在实验前测定了分泌物的 Cd 络合特性，以确保所有 Cd 都以有机络合物的形式提供给生物体。结果表明，游离的 Cd2+ 离子对细菌的毒性最高，而与蓝藻分泌物络合的 Cd 毒性较低，但可以生物利用，并通过食物网传递。本研究为水生生态系统管理和当前 Cd 动态、生物利用度以及与水生浮游生物相互作用的知识做出了贡献。
